In recent years, a tactile sense presenting device which gives a feedback of touch and a feeling of a keystroke by transmitting vibrations when the user touches a key on a touch panel keyboard has been proposed as an example of a vibrating device.
For example, Patent Document 1 discloses a structure which holds both ends of a piezoelectric bimorph element composed of piezoelectric ceramics or the like by using a low elastic body, and connects a vibrated body to a center of the piezoelectric bimorph element. The structure of Patent Document 1 transmits vibrations to a user via the connected vibrated body by inputting an alternating-current drive signal to the piezoelectric bimorph element to cause vibration.
Further, in some tactile sense presenting devices, a diaphragm is, for example, fixed to a piezoelectric film in a warped state. A touch sensor which detects a touch operation is provided on a principal surface of the diaphragm. This tactile sense presenting device applies a drive signal to the piezoelectric film in response to a user's touch operation, and the piezoelectric film stretches or contracts. When the piezoelectric film stretches or contracts, the diaphragm vibrates, and this vibration transmits to the user.
Patent Document 1: Japanese Patent Application Laid-Open No. 2005-303937